Effect Of Continuous Femoral Nerve Block On Pain Score, Rehabilitation And Stress Response After Total Knee Arthroplasty

OBJECTIVETo assess the influence of continuous femoral nerve block (CFNB) and IV patient-controlled analgesia (PCIA) on postoperative pain scores, knee rehabilitation and stress response after total knee arthroplasty (TKA).METHODSThe trial was designed as a randomized and controlled study. Before standardized general anesthesia, 32 adult patients scheduled for elective total knee arthroplasty were randomly assigned to CFNB group or PCIA group to receive a different postoperative analgesic technique for 48 hours. Pain was assessed at rest and during continuous passive motion (CPM) using a visual analog scale at PACU and 4, 8,12,24,48 hours postoperatively and morphine consumption was also recorded. The maximal amplitude of knee flexion was measured during CPM in the first postoperative day (POD1) and POD2. As indicators of stress and inflammatory response, changes in the leukocyte count, serum lactic acid, blood glucose, serum C-reactive protein(CRP) and serum cortisol were determined on admission to OR, immediately after skin incision, before extubation, POD1 and POD2, respectively.RESULTSIntraoperative consumption of fentanyl was significantly lower in CFNB group than in PCIA group, (137.5±44.4 ug vs. 264.1±67.1 ug, respectively, P<0.05) . The CFNB group showed significantly lower VAS scores both at rest and during CPM compared with PCIA group at all time points (P<0.05) . Morphine consumption was significantly lower in CFNB group than in PCIA group (P<0.05) . The incidence of side effects such as somnolence, nausea and vomiting in CFNB group was half of that of PCIA group. The CPM amplitude of CFNB group was significantly larger compared with PCIA group on both POD1 and POD2 (P<0.05) . Patient satisfaction was higher in CFNB group than in PCIA group, (93.1±7.9 vs. 79.1±11.9, respectively, P<0.05) . No significant differences were observed between the groups in circulating levels of leukocyte count, serum lactic acid, blood glucose, serum C-reactive protein(CRP) and serum cortisol.CONCLUSIONSIn this study, we determined that, after TKA, CFNB technique provides better pain relief and faster postoperative knee rehabilitation than traditional PCIA. A single CFNB can not attenuate the postoperative stress and inflammatory responses.